Drawer for storage cabinet or storage unit

ABSTRACT

A drawer comprising a pair of sidewalls wherein each sidewall has a pair of widthwise end portions, and an exterior side. The exterior side has a plurality of pairs of tracks extending generally perpendicular to the longitudinally extending axis wherein each pair of tracks defines a channel. Each widthwise end portion defines a channel on the exterior side. Each sidewall has a plurality of openings adjacent the bottom lengthwise end of the sidewall. The draw further includes a pair of insert members. Each insert member is removably attached to a corresponding drawer sidewall. Each insert member has a front side and a rear side that confronts the sidewall, a pair of flanged widthwise ends, a bottom lengthwise end, and a plurality of rails on the rear side. Each rail is slidably disposed within a corresponding channel. Each insert member has a plurality of protrusions that are frictionally and removably inserted into corresponding openings in the corresponding sidewall.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention generally relates to a storage cabinets.

[0003] 2. Description of Related Art

[0004] Multi-drawer or multi-tray cabinets or storage units are used in industry for storing a variety of components such as screws, nuts, washers, electrical components, etc. Such cabinets are also used in retail establishments as such hardware stores. Examples of such drawers, trays, cabinets and other storage units are described in U.S. Pat. Nos. 3,866,993, 3,954,315, 4,440,461, 4,838,627, 5,632,542, 5,664,856, 5,823,650 and 6,076,908. Prior art multi-drawer cabinets are typically fabricated from metal and generally comprise a metal box-like housing and a plurality of drawers or trays that are slidably disposed within the housing. The multi-drawer cabinets include a plurality of pairs of interior slides that are attached to the inner walls of the cabinet or housing of the storage unit. Specifically, one of the interior slides is attached to inner sidewall of the cabinet and the other interior slide is attached to the opposite cabinet sidewall. The interior slides of each pair are aligned with one another. Each drawer has a pair of sidewalls and a corresponding pair of drawer outer slides that are rigidly attached to the exterior sides of the opposing sidewalls and slidably engaged to the interior slides. Thus, the drawer can be slid into and out from the interior of the cabinet housing.

[0005] One disadvantage of the conventional drawer configuration described above is that the process of attaching the drawer outer slides to the exterior sides of the opposing sidewalls of the drawer is time consuming and as a result, increases the production costs of the drawer. Furthermore, if any of the drawer outer slides becomes damaged, the entire drawer must be replaced. The drawer is then either discarded or taken back to the factory for repair. Either one of these options is cost-inefficient, time consuming and disruptive.

[0006] It is therefore an object of the present invention to provide a new and improved cabinet drawer or tray that solves the aforementioned problems.

[0007] It is another object of the present invention to provide a new and improved cabinet drawer or tray that can be manufactured at reasonable costs.

[0008] Other objects and advantages of the present invention will be apparent to one of ordinary skill in the art in light of the ensuing description of the present invention.

SUMMARY OF THE INVENTION

[0009] The present invention is directed to, in one aspect, a drawer comprising a pair of opposite sidewalls wherein each sidewall comprises a longitudinally extending axis, a pair of widthwise end portions, an exterior side, and an interior side facing the opposite sidewall. The exterior side of each sidewall further includes a plurality of pairs of tracks extending generally perpendicular to the longitudinally extending axis. Each pair of tracks defines a channel. Each widthwise end portion defines a channel on the exterior side. Each sidewall further includes a plurality of openings. The drawer further includes a pair of insert members. Each insert member is removably attached to the exterior side of a corresponding drawer sidewall. Each insert member has a longitudinally extending axis, a front side, a rear side confronting the exterior side of the corresponding drawer sidewall, a pair of flanged widthwise ends, a top lengthwise end, a bottom lengthwise end, and plurality of rails on the rear side. Each rail is slidably disposed within a corresponding channel on the exterior side of the corresponding sidewall. The insert member further includes a plurality of openings. Each opening has a perimetrical edge and is located at a predetermined position with respect to the longitudinally extending axis of the insert member. Each insert member further includes a plurality of protrusions extending from the rear side. Each protrusion is frictionally and removably inserted into a corresponding one of the openings in the corresponding sidewall. The tracks on the exterior side of the sidewall and the rails of the rear side of the insert member cooperate to define a space between the sidewall and the insert member. The positioning of the (i) rails of each insert member within the channels of the corresponding sidewall, and (ii) flanged widthwise ends of the insert member within the channels defined by the widthwise ends of the drawer sidewall, and the frictional insertion of the protrusions of the insert member in the openings of the corresponding sidewall cooperate to substantially eliminate upward, downward and lateral movement of the insert member with respect to the corresponding sidewall thereby effecting firm but removable attachment of the insert member to the corresponding drawer sidewall.

[0010] The drawer further includes a pair of outer slide members. Each outer slide member is removably attached to the exterior side of a corresponding insert member. Each outer slide has a longitudinally extending axis and a plurality of protruding members. Each of the protruding members is removably disposed within a corresponding one of the openings of the insert member and engages a portion of the perimetrical edge of the corresponding opening.

[0011] In a related aspect, the present invention is directed to a drawer comprising a pair of opposite sidewalls, each sidewall having a longitudinally extending axis, a pair of widthwise end portions, an exterior side, an interior side facing the drawer interior, the exterior sides of each sidewall having a plurality of pairs of tracks extending generally perpendicular to the longitudinally extending axis, each pair of tracks defining a channel, each widthwise end portion defining a channel on the exterior side, each sidewall having a plurality of openings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The features of the invention are believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The invention itself, however, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which:

[0013]FIG. 1 is an exploded perspective view of the drawer of the of the present invention.

[0014]FIG. 2 is a perspective view of the assembled drawer of the present invention.

[0015]FIG. 3 is a top plan view of the drawer of FIG. 1.

[0016]FIG. 4 is a front view taken along line 4-4 in FIG. 3.

[0017]FIG. 5 is a side view taken along line 5-5 in FIG. 3, the insert member depicted in FIGS. 1 and 2 not being shown so as to facilitate viewing a sidewall depicted in FIG. 1.

[0018]FIG. 6 is a bottom view of the drawer shown in FIG. 2.

[0019]FIGS. 6A, 6B and 6C are enlarged views of certain portions of the view of FIG. 6.

[0020]FIG. 6D is a view taken along line 6D-6D of FIG. 6B.

[0021]FIG. 7 is a perspective view of the insert member depicted in FIGS. 1 and 2.

[0022]FIG. 8 is a front view of the insert member of FIG. 7.

[0023]FIG. 9 is an end view taken along line 9-9 in FIG. 8.

[0024]FIG. 10 is a rear view of the insert member of FIG. 7.

[0025]FIG. 11 is a top view taken along line 11-11 of FIG. 8.

[0026]FIGS. 12a, 12 b and 13 are enlarged views of certain portions of the view of FIG. 11.

[0027]FIG. 14 is a bottom end view taken along line 14-14 in FIG. 10.

[0028]FIG. 15 is a side elevational view of an outer slide member that is removably attached to the insert member shown in FIG. 7.

[0029]FIG. 16 is an end view taken along line 16-16 in FIG. 15.

[0030]FIG. 17 is a bottom end view taken along line 17-17 in FIG. 15.

DETAILED DESCRIPTION OF THE INVENTION

[0031] In describing the preferred embodiments of the present invention, reference will be made herein to FIGS. 1-17 of the drawings in which like numerals refer to like features of the invention.

[0032] Although the ensuing description is in terms of a “drawer”, it is to be understood that the features and concept of the present invention are also applicable to trays that are used in multi-tray cabinets or storage units.

[0033] Referring to FIGS. 1-6, there is shown drawer 10 of the present invention. Drawer 10 generally comprises bottom 12, outer sidewalls 14 and 16, front wall 18 and rear wall 20. Drawer 10 further includes interior 22 and equidistantly spaced inner walls 24. Front wall 18 includes beveled top lengthwise end 25. Drawer 10 further includes removable dividers or partitions 26 that are slidably engaged within tracks 28 on inner walls 24.

[0034] Referring to FIGS. 1, 5, 6, and 6A-6D, sidewalls 14 and 16 are identical in construction and therefore, for purposes of brevity and simplification, only sidewall 14 is described in the ensuing description. FIG. 6A is an enlarged view of the portion of the view of FIG. 6 indicated by dotted line 47 a. FIG. 6B is an enlarged view of a portion of the view of FIG. 6 indicated by dotted circle 47 b. FIG. 6C is an enlarged view of a portion of the view of FIG. 6 indicated by dotted circle 47 c. Sidewall 14 has front widthwise end 30 and rear lengthwise end 32. Sidewall 14 includes interior side 34, exterior side 36, and top lengthwise end 38. Sidewall 14 includes a plurality of pairs of tracks 40 on exterior side 36. Each pair of tracks 40 defines a channel 42. In one embodiment, tracks 40 are attached to exterior side 36. In another embodiment, tracks 40 are integrally formed with sidewall 14 during fabrication of sidewall 14. In a preferred embodiment, each pair of tracks 40 are equidistantly spaced. As shown in FIGS. 5, 6A and 6C, sidewall 14 further includes single track 44 and single track 46. Single track 44 is adjacent end 30. Single track 46 is adjacent to end 32. Track 44 and wall 18 define channel 50. Track 46 cooperates with wall 20 to define channel 52. Referring to FIG. 6D, sidewall 14 includes a stepped portion 53 that has front surface 53 a. Sidewall 14 further includes openings 54 therein. In a preferred embodiment, openings 54 are equidistantly spaced. In one embodiment, openings are generally rectangular shaped. The purpose of openings 54 is—explained in the ensuing description.

[0035] Referring to FIGS. 7-14, there is shown insert member 60 that is configured to be removably attached to sidewall 14. Insert member 60 is also shown in FIGS. 1 and 2. Drawer 10 utilizes an additional insert member, which is identical to insert member 60, that is removably attached to outer sidewall 16. However, for purposes of brevity and simplicity, only insert member 60 is described in the ensuing description. Insert member 60 comprises longitudinally extending axis 61, front side 62, rear side 64, top lengthwise end 66, bottom lengthwise end 68, flanged widthwise end 70 and flanged widthwise end 72. Referring to FIG. 9. insert member 60 has a width W1. Insert member 60 includes upper portion 74 that has width W2 that is less than width W1. The difference in widths W1 and W2 provide ledge 75 which is contiguous with surface 76. The purpose of such a configuration is explained in the ensuing description.

[0036] Referring to FIG. 10, insert member 60 further includes a plurality of protrusions 80. Protrusions 80 are aligned with openings 54 of sidewall 14 (see FIG. 5). Each protrusion 80 is shaped and sized to frictionally fit into a corresponding opening 54 on sidewall 14. In a preferred embodiment, each protrusion 80 is generally rectangular shaped. In a preferred embodiment, protrusions 80 are equidistantly spaced. Thus, in such a configuration, protrusions 80 function as male engagement regions and openings 54 function as complementary female engagement regions.

[0037] Referring to FIGS. 11-14, insert member 60 includes a plurality of rails 82 on rear side 64. Each rail 82 is sized to be slidably disposed within a corresponding channel 42 on sidewall 14 (see FIG. 6B). FIG. 13 is an enlarged portion of the view of FIG. 11 indicated by dashed circle 83. Referring to FIGS. 7, 10, 11, 12 a and 12 b, insert member 60 includes flanged widthwise end 70 and flanged widthwise end 72. FIG. 12a is an enlarged view of a portion of the view of FIG. 11 indicated by dashed circle 87 a. FIG. 12b is an enlarged view of a portion of the view of FIG. 11 indicated by dashed circle 87 b. Flanged end 70 is sized to be slidably disposed within channel 50 formed by track 44 (see FIG. 6C). Similarly, flanged end 72 is sized to be slidably disposed in the channel 52 formed by track 46 (see FIG. 6A).

[0038] Referring to FIGS. 10-12, insert member 60 includes a plurality of engagement regions 92, 94, 96 and 98. In a preferred embodiment, each engagement region 92, 94, 96 and 98 comprises an opening. In one embodiment, each engagement region 92, 94, 96, and 98 comprises a generally square-shaped opening. However, other suitable shapes may be used. Each opening 92, 94, 96 and 98 has a perimetrical edge 100. A portion of the perimetrical edge 100 of opening 92 is designated as edge 100 a. A portion of the perimetrical edge 100 of opening 94 is designated as edge 100 b. A portion of the perimetrical edge 100 of opening 96 is designated as edge 100 c.

[0039] In a preferred embodiment, opening 98 is the smallest in size. The purpose of such a configuration is discussed in the ensuing description. Insert member 60 further includes reinforcing ribs 102 which provide structural support and integrity to insert member 60.

[0040] Referring to FIGS. 8 and 10, each opening 92, 94, 96 and 98 is positioned in a predetermined position with respect to longitudinally extending axis 61. Opening 94 is positioned adjacent bottom lengthwise end 68 and between a pair of reinforcing ribs 102. Similarly, opening 96 is positioned adjacent bottom lengthwise end 68 and between a pair of reinforcing ribs 102. Opening 92 is positioned adjacent to reinforcing rib 102 a. Opening 98 is positioned a predetermined distance away from reinforcing rib 102 b.

[0041] Referring to FIGS. 1, 7, 10, 12 a, 12 b, 13 and 14 in order to removably attach insert member 60 to sidewall 14 of drawer 10, insert member 60 is positioned so that it is beneath sidewall 14, front side 62 faces outward, each rail 82 is aligned with a corresponding channel 42, and flanged ends 70 and 72 are aligned with channels 50 and 52, respectively (see FIGS. 6A and 6C). Insert member 60 is then maneuvered so that rails 82 enter channels 42 and flanged ends 70 and 72 are inserted into channels 50 and 52, respectively. Insert member 60 is then moved with respect to sidewall 14 so that:

[0042] (i) rails 82 are completely inserted into channels 42;

[0043] (ii) flanged ends 70 and 72 are completely inserted into channels 50 and 52, respectively;

[0044] (iii) protrusions 80 are inserted into openings 50; and

[0045] (iv) surface 76 of portion 74 of insert member 60 (see FIG. 9) is positioned over surfaces 53 a of sidewall 14 (see FIG. 6D). As insert member 60 is slid on sidewall member 14, protrusions 80 of insert member 60 frictionally slide along side 36 of sidewall 14 until protrusions 80 snap into corresponding openings 54 in sidewall 14.

[0046] In order to remove insert member 60 from sidewall 14, bottom edge 68 of insert member 60 is first pried away from sidewall 14 so as to withdraw protrusions 80 from openings 54. Next, insert member 60 is slid off of sidewall 14 so rails 82 are completely withdrawn from channels 42 and rails 70 and 72 are completely withdrawn from channels 50 and 52, respectively.

[0047] The storage cabinet. housing or storage unit (not shown) with which drawer 10 is used utilizes interior slides that are typically rigidly attached to the inner walls of the cabinet, housing or storage unit as described in the foregoing description. Outer slide members are moveably attached to the interior slides. Such interior and outer slide members are generally described in U.S. Pat. No. 6,076,908, the disclosure of which is incorporated herein by reference. However, the aforementioned patent is cited merely to show the general operation of such interior and outer slides.

[0048] In accordance with invention, completely assembled drawer 10 (see FIG. 2) is slidably mounted within a cabinet, housing or other structure (not shown). Sin order to accomplish this, a pair of slide members are removably attached to the insert member (e.g. insert member 60) which are removably attached to sidewalls 14 and 16 of drawer 10. One embodiment of such an outer slide member is shown in FIGS. 16-17. Outer slide member 120 generally comprises front side 122, rear side 124, top lengthwise end 126, bottom lengthwise end 128 and protruding members 130, 132, 134 and 136. Outer slide 120 includes longitudinally extending axis 138. Each protruding member 130, 132, 134 and 136 is positioned at a predetermined position with respect to axis 138. Specifically, axis 138 generally bisects protruding members 132, 134 and 136 and extends through a portion of protruding member 130. Protruding member 136 comprises a lip that extends in the direction of longitudinal axis 138. Protruding member 136 has generally the same configuration as engagement region 66 shown in FIGS. 3 and 3a of U.S. Pat. No. 6,076,908. Each protruding member 132 and 134 comprises a lip that extends generally upward. Protruding members 132 and 134 have generally the same configuration as engagement region 68 shown in FIGS. 3 and 3b of U.S. Pat. No. 6,076,908 with the exception that protruding members 132 and 134 of the present invention extend upward rather downward. Protruding members 132 and 134 extend in a direction that is generally perpendicular to axis 138.

[0049] Referring to FIGS. 2, 8 and 15, in order to removably attach outer slide 120 to insert member 60, slide 120 is positioned so that protruding members 130, 132, 134 and 136 confront side 62 of insert member 60. Slide 120 is then maneuvered so that protruding member 136 is inserted into opening 92 of insert member 60. Outer slide 120 is then maneuvered so that protruding member 132 is disposed in opening 96 of insert member 60, and protruding member 134 disposed within opening 94. The space existing between sidewall 14 and insert member 60 is sized to receive protruding members 132, 134 and 136 when these protruding members are inserted through openings 96, 94 and 92, respectively. Once protruding members 132, 134 and 136 are inserted through openings 96, 94 and 92, respectively, the user applies force to outer slide 120 in order to frictionally insert protrusion 130 into opening 98 of insert member 60.

[0050] The predetermined positions of openings 92, 94, 96 and 98, with respect to bottom edge 68 of insert member 60, and the predetermined positions of protruding members 132, 134 and 136, with respect to axis 138, provide for a tight fitting attachment of outer slide 120 to insert member 60. Thus, when protruding members 130, 132, 134 and 136 are completely inserted through openings 98, 96, 94 and 92, respectively, protruding member 136 firmly abuts edge 100 a of opening 92, protruding member 132 firmly abuts edge 100 c of opening 96, protruding member 134 firmly abuts edge 100 b of opening 94, and protruding member 130 is frictionally inserted into opening 98.

[0051] In order to remove outer slide 120 from insert member 60, the user pries outer slide 120 away from insert member 60 SO as to withdraw protruding member 130 from opening 98. The user then maneuvers outer slide 120 with respect to insert member 60 SO as to cause protruding members 132, 134 and 136 to be withdrawn from openings 96, 94 and 92, respectively.

[0052] Drawer 10 can be fabricated from a variety of materials, e.g. metal, plastic, etc. In a preferred embodiment, drawer 10 is fabricated from plastic. Such suitable plastics include ABS, GPPS, Crystal Styrene, HDPE, HIPS, Nylon, PC, PCABS, PE, PP and SAN.

[0053] Thus, the improved drawer 10 of the present invention allows for the easy removal and replacement of insert member 60. Furthermore, drawer 10 of the present invention allows streamlining of production lines, decreases the per-unit fabrication time, and improves production yield. Furthermore, drawer 10 of the present invention allows for easy replacement of damaged drawer outer slides, eliminates the need for factory refitting of drawers or discarding drawers with damaged drawer outer slides, can be configured to fit cabinets or varying sizes, and can be manufactured at a reasonable costs.

[0054] While the present invention has been particularly described, in conjunction with a specific preferred embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. It is therefore contemplated that the appended claims will embrace any such alternatives, modifications and variations as falling within the true scope and spirit of the present invention. 

Thus, having described the invention, what is claimed is:
 1. A drawer comprising: a pair of opposite sidewalls, each sidewall having a longitudinally extending axis, a pair of widthwise end portions, an exterior side, an interior side facing the drawer interior, the exterior side of each sidewall having a plurality of pairs of tracks extending generally perpendicular to the longitudinally extending axis, each pair of tracks defining a channel, each widthwise end portion defining a channel on the exterior side, each sidewall having a plurality of openings; and a pair of insert members, each of which being removably attached to the exterior side of a corresponding drawer sidewall, each insert member having a longitudinally extending axis, a front side, a rear side confronting the exterior side of the corresponding sidewall, a pair of flanged widthwise ends, a top lengthwise end, a bottom lengthwise end, and plurality of rails on the rear side, each rail being slidably disposed within a corresponding channel on the exterior side of the corresponding sidewall, the insert member further including a plurality of openings, each opening having a perimetrical edge and being located at a predetermined position with respect to the longitudinally extending axis of the insert member, each insert member having a plurality of protrusions extending from the rear side, each protrusion being frictionally and removably inserted into a corresponding one of the openings in the corresponding sidewall, the tracks on the exterior side of the sidewall and the rails of the rear side of the insert member cooperating to define a space between the sidewall and the insert member; the positioning of the (i) rails of each insert member within the channels of the corresponding sidewall, and (ii) flanged widthwise ends of the insert member within the channels defined by the widthwise ends of the sidewall, and the frictional insertion of the protrusions of the insert member in the openings of the corresponding sidewall cooperating to substantially eliminate upward, downward and lateral movement of the insert member with respect to the corresponding sidewall thereby effecting firm but removable attachment of the insert member to the corresponding drawer sidewall.
 2. The drawer according to claim 1 further comprising a pair of outer slides, each outer slide being removably attached to the exterior side of a corresponding insert member, each outer slide having a longitudinally extending axis and a plurality of protruding members, each of the protruding members being removably disposed within a corresponding one of the openings of the insert member and engaging a portion of the perimetrical edge of the corresponding opening.
 3. The drawer according to claim 2 wherein a first one of the protruding members has a lip that laterally extends in a direction that is generally parallel to the longitudinally axis of the outer slide member and which is disposed through a corresponding opening of the insert member and is positioned within the space existing between the insert member and the sidewall, a second one of the protruding members having a lip that extends upward in a direction that is generally perpendicular to the longitudinal axis of the outer slide member and disposed through a corresponding opening of the insert member and positioned within the space existing between the insert member and the sidewall, a third one of the protruding members having a lip that extends upward in a direction that is generally perpendicular to the longitudinal axis of the outer slide member and is disposed through a corresponding opening of the insert member and is positioned within the space existing between the insert member and the sidewall, a forth one of the protruding members comprising a tab that extends outwardly from the exterior side of the insert member and is frictionally inserted into a corresponding one of the openings on the insert member, the orientation and positioning of (i) the openings of each insert member with respect to the longitudinally extending axis of each insert member, and (ii) the protruding members with respect to the longitudinally extending axis of each outer slide cooperating with the frictional insertion of the tab within the corresponding opening in the insert member to effect firm but removable attachment of the outer slides to the insert members.
 4. The drawer according claim 1 wherein the openings on the sidewall are equidistantly spaced apart.
 5. The drawer according to claim 2 wherein the insert member further includes a plurality of reinforcing ribs on the rear side thereof, the ribs extending generally parallel to the rails.
 6. The drawer according to claim 2 wherein the protrusions on the rear side of the insert member are adjacent to the bottom lengthwise end.
 7. The drawer according to claim 6 wherein the protrusions are equidistantly spaced.
 8. The drawer according to claim 2 wherein the tab has a perimeter.
 9. The drawer according to claim 8 wherein each outer slide has a longitudinally extending axis that bisects the outer slide, the protruding members of the outer slide being positioned relative to the longitudinally extending axis of the outer slide such that this axis (i) bisects the first one of the protruding members, (ii) extends through the second one of the protruding members, (iii) extends through the third one of the protruding members, and (iv) generally overlaps a portion of the perimeter of the tab.
 10. The drawer according to claim 1 wherein the drawer and insert member are fabricated from plastic chosen from the group comprising ABS, GPPS, Crystal Styrene, HDPE, HIPS, Nylon, PC, PCABS, PE, PP and SAN.
 11. An insert member for removable attachment to an exterior side of a drawer sidewall, the insert member having a longitudinally extending axis, a front side, a rear side, a pair of flanged widthwise ends, a top lengthwise end, a bottom lengthwise end, and plurality of rails on the rear side, the rails extending generally perpendicular to the longitudinally extending axis, the insert member further including a plurality of openings, each opening being located at a predetermined position with respect to the longitudinally extending axis, the insert member having a plurality of protrusions that extend from the rear side and which are adjacent the bottom lengthwise end, the insert member further including a plurality of reinforcing ribs on the rear side thereof, the ribs extending generally parallel to the rails.
 12. The drawer according to claim 10 wherein the protrusions are equidistantly spaced.
 13. A drawer comprising a pair of opposite sidewalls, each sidewall having a longitudinally extending axis, a pair of widthwise end portions, an exterior side, an interior side facing the drawer interior, the exterior side of each sidewall having a plurality of pairs of tracks extending generally perpendicular to the longitudinally extending axis, each pair of tracks defining a channel, each widthwise end portion defining a channel on the exterior side, each sidewall having a plurality of openings. 